rank the following causes of death from highest to lowest probability earthquake lightning stroke...

© 2014 John Wiley & Sons, Inc. All rights reserved.

Rank the following causes of death from highest to lowest probability

• Earthquake• Lightning• Stroke• Firearm assault• Drowning• Cancer

• Falling• Fireworks discharge• Motor vehicle accident• Hornet/wasp/bee sting• Heart disease• Hot weather


What is a greater risk?Dying from a disease like measles, diphtheria, and whooping cough?

OR

Being harmed by the chemicals in vaccines?

http://video.pbs.org/video/2365449467/



Visualizing Environmental Science

Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

Risk Analysis and Environmental Health

Hazards

Chapter 7[chapter opener image]

Chapter 4


Pesticides and Children• More harmful to children than

adults– Greater exposure

• Playing in contaminated fields• Putting hands/objects in mouth

– Greater response• Developing bodies more sensitive

• Range of effects– Cancer, mental and/or physical

disabilities• Intelligence• Motor skills


A Perspective on Risks• Risk

– The probability of harm (human or environmental) occurring under certain circumstances

– Inherent in our actions and our environment

– Risk management is the process of identifying, assessing, and reducing risks


A Perspective on Risks• In order to

successfully manage risks, we must have a sense of their:– Causes– Likelihoods – Effects

Quantitative Measures of Risk

• Probabilities – a mathematical statement about the likelihood of harm

• Can be expressed in three ways:– 1:100– 1/100– “One in one hundred”

Quantitative Measures of Risk

• Ex: 1:6,210 - risk of dying from alcohol– (1 person in 6,210 people will die of alcohol related illness)

• The bigger the bottom number (denominator) the less the chance– Ex: chance of winning Power Ball lottery: about 1 in 80,000,000 – Ex: chance of laughing at with Mr. Strogen today: about 1 in 3


Four Steps for Risk Assessment• Risk assessment: quantitative and qualitative

characterization of risks in order to manage1. Hazard identification

• Can exposure have adverse health effects?2. Dose-response assessment

• What is the relationship between the amount and the response?

3. Exposure assessment• How often are individuals exposed?

4. Risk characterization• Leads to risk management


A Curious Dilemma • People are more concerned

about small risks than large risks – Large risk: complications

associated with smoking– Small risk: EPA-permitted amounts

of carcinogenic chemicals in water– Average life expectancy is reduced

by 8 years for smokers and 1/3 of smokers die from related-illness

– A smoker is 300,000 times more likely to get cancer from smoking than to get it from ingesting a low level of trichloroethylene in their water


A Curious Dilemma • People seem to be far more

concerned about small risks than about large risks

• Why the difference in concern? – Habit and culture (vs.

analysis)– Perception of risks – Trust in institutions– Feeling that some risks

cannot be controlled


Are more teenagers smoking cigarettes today compared to 20

years ago?


An Example of High Risk: Lung Cancer• Data suggests that smoking is

on the decline among younger people, although the poor and some minority groups have disproportionally high smoking rates

• The graph shows the percentage of U.S. students (grades 9–12) who smoked cigarettes on at least 1 or 2 of the past 30 days

• In what year did smoking peak among males? Females?


Risky Behavior – “Fun” Facts• The percentage of high school students who had been in a physical fight at

least once during the past year decreased from 42% in 1991 to 25% in 2013• 41% of students who had driven a car or other vehicle during the past 30

days reported texting or emailing while driving• The percentage of high school students who are currently sexually active

has declined from 38% in 1991 to 34% in 2013• From 2003−2013, the percent of high school students using a computer 3 or

more hours per day (for non-school related work) nearly doubled from 22% to 41%

• The percentage of high school students who watch 3 or more hours of TV on an average school day decreased since 1999 (from 43% to 32%)

• There was a significant decrease in drinking soda 1 or more times per day from 34% in 2007 to 27% in 2013

http://www.cdc.gov/media/releases/2014/p0612-yrbs.html





Environmental Health Hazards

• Toxicants– Chemicals with adverse effects on health– All chemicals are toxic if exposure is high enough

• “The dose makes the poison”

• Toxicology – Studies the effects of toxicants on living organisms– Evaluates the mechanisms that cause toxicity– Develops ways to prevent or minimize adverse

effects


Environmental Health Hazards• Epidemiology

– The study of how toxicants, biological agents (disease), and physical agents (accidents, radiation) affect the health of human populations

– Studies large groups of people and investigates range of causes and types of disease and injuries

– Toxicant exposure can be acute or chronic


Environmental Health Hazards•Acute toxicity

Immediate effects after a single short period, high-level exposure Symptoms include dizziness, nausea, death

•Chronic toxicityProlonged effects to long-term, low-level exposureSymptoms can mimic other chronic diseaseWe know much less about chronic toxicity

Toxicology Studies

• Retrospective studies– “Looking back” – Monitoring people who have already been exposed to a chemical to determine the effects

• Prospective studies– “Looking forward”– Monitoring people who might become exposed to a chemical to determine the effects

Biological Risks

• Infectious diseases: those caused by disease-causing infectious organisms, known as pathogens– Ex: pneumonia and

venereal diseases

Pathogens• Bacteria:

– Cholera– Tuberculosis– Syphilis

• Virus:– HIV/AIDS– Hepatitis– Ebola

• Protozoa:– Malaria

http://sustainabledesignupdate.com/wp-content/uploads/2007/11/bacteria.jpg

What causes disease?• Infectious agents (pathogens) that are spread by:

– Air– Water– Food– Body fluids– Vectors (nonhuman carriers, like mosquitoes)

http://itodyaso.wordpress.com/2008/03/02/emeringing-hcurch-is-a-disease-medical-proof/122/

Pathways of Transmitting Pathogens


Disease-Causing Agents in the Environment

• Sewage-contaminated water– Environmental threat to public health– Drinking water is periodically tested for

fecal coliform bacteria (such as E. coli)• 1993, U.S. outbreak of Cryptosporidium

– https://www.youtube.com/watch?v=mu_EZJ3vFSg

• 2000, waterborne E. coli outbreak in Canada

• 2009, cholera outbreak in Zimbabwe• 2010, cholera outbreak in Haiti

https://www.youtube.com/watch?v=mu_EZJ3vFSg

https://www.youtube.com/watch?v=mu_EZJ3vFSg

Fecal Coliform Bacteria

Fecal coliform bacteria – group of bacteria found in the intestines and feces of vertebrate animals

Escherichia coli (E. coli) is usually the bacteria tested for – its presence indicates a risk of other wastewater pathogens

(<1 bacterium per 100 mL of water)

Water Facts Every 20 seconds, a child dies from a water-related

illness in the world More than 3 times as many people lack access to

clean water than live in the United States More people have cell phones worldwide than have

access to a toilet Half of the hospital beds in the world are occupied by

patients suffering from diseases associated with lack of access to safe drinking water, inadequate sanitation, and poor hygiene

Courtesy of water.org

Water Facts Diarrhea is the second leading cause of death among

children under five in the world; it kills more children than malaria, AIDS, and measles combined

Of the 60 million people added to the world's towns and cities every year, most move to informal settlements (i.e. slums) with no sanitation facilities

An American taking a five-minute shower uses more water than the average person in a developing country slum uses for an entire day

1.1 billion people still practice open defecation In 3 days, the amount of untreated fecal matter in the world

would fill up the SuperdomeCourtesy of water.org

Common Diseases from Human Wastewater Cholera is a bacterial disease (Vibrio cholerae) often

transmitted by drinking contaminated water Symptoms include: severe diarrhea, vomiting, and leg

cramps 100,000-120,000 deaths every year from cholera

Common Diseases from Human Wastewater

Typhoid fever is a bacterial disease (Salmonella typhi) often transmitted by drinking contaminated water

Symptoms include: high fever, malaise, headache, constipation or diarrhea

Common Diseases from Human Wastewater Hepatitis A and E are infections of the liver by

viruses, spread through water or food Symptoms include: fever, fatigue, nausea,

vomiting, abdominal pain


Some Human Diseases Transmitted by Polluted Water

• Thinking Skill: Explicitly assess information and draw conclusions

• Objective: Describe the effect of toxins that are transported throughout the environment

11-19-15


What effect will climate change have on the spread of diseases?


Environmental Changes and Emerging Diseases

• 25% of injury and disease worldwide is related to human-caused environmental changes

• Climate change gives disease-causing agents the opportunity to thrive

• Cutting forests, building dams and agriculture may bring us into contact with disease-causing agents and increasing populations of disease-carrying organisms such as mosquitoes


Social Factors Contribute to Disease Epidemics

• Drainage ditches on each side of this road clearing in the Amazon rain forest are a breeding ground for mosquito larvae

• Global travel has contributed to the rapid spread of disease over great distances

• Highly concentrated urban populations promote rapid spread of disease among large numbers of people


Social Factors Contribute to Disease Epidemics

• Diseases carried by animals– Malaria and West Nile

Virus spread by mosquitoes– Lyme disease spread by

deer ticks– Bubonic plague spread by

rats and fleas

Emergent Diseases


Environmental Health Hazards• Pandemic

– Disease reaches nearly all parts of the world• Influenza (flu)• Avian influenza affects birds and then infects humans

– Hard to transmit to humans, but once infected, human mortality is high

• H1N1 (Swine) Flu - https://www.youtube.com/watch?v=lFl3FRNpU4E – Late Spring 2009, Mexico– Pandemic by early Summer

– Understanding and controlling pandemics requires:• Understanding of the environment and conditions that allow

the virus to survive and travel• Cooperation among many governments and individuals

https://www.youtube.com/watch?v=lFl3FRNpU4E

https://www.youtube.com/watch?v=lFl3FRNpU4E


People and Livestock in Close Proximity• Avian influenza difficult to

transfer from human to human, more common bird to human

• Swine flu transferred from pigs, 2009 Mexico outbreak

• Children in rural China live and play near livestock– Pigs and chickens share

enough genetic similarities to facilitate disease transfer

Movement and Fate of Toxicants• Some toxicants are

particularly dangerous– Resist degradation– Travel quickly in the

environment• DDT

– A pesticide banned in the U.S. in 1972

– Causes birds to lay eggs with thin shells

– Very persistent and can bioaccumulate in organisms © 2014 John Wiley & Sons, Inc. All rights reserved.

Environmental InSight• Persistence: how long a chemical remains in

the environment until it breaks down


Environmental InSight• Bioaccumulation

– Chemical stored in organisms with higher concentrations found at the top of the food chain

• Biological magnification– Increased concentration as toxicant

passes through levels of the food chain

– Note how the level of DDT increased in the tissues of various organisms as DDT moved through the food chain


Biomagnification


Mobility of Pesticides in the Environment

• Toxicants can move through soil, water, air• Agricultural pesticides runoff into rivers and streams,

harming aquatic life– Adverse effects on aquatic

plants and animals, like bone degeneration in fish


Environmental Working Group

• This watch-dog organization analyzed five common herbicides found in drinking water

• 3.5 million people in the Midwest have elevated cancer risk due to exposure to herbicides

• EPA has mandated a reduction in the use of those herbicides


• Stockholm Convention on Persistent Organic Pollutants, 2001– UN treaty to protect human

health from the 12 most toxic persistent organic pollutants (POPs)

– Requires countries to develop plans to eliminate the production and use of intentionally produced POPs

• Exception: DDT

Global Ban of Persistent Organic Pollutants


Determining Health Effects of Pollutants• Toxicity determined by the

dose that produced adverse effects

• Dose– The amount of a toxicant

that enters the body• Response

– Type and amount of damage to a particular dose

– Lethal dose: causes death – Sub-lethal dose: causes harm

Toxicology

• Dose: the amount of a substance that a person has in their body– Can be:

• Ingested• Inhaled• Injected • Absorbed

• “The dose makes the poison”


• Different doses of chemical administered to populations of laboratory animals

• Data findings used to predict effects on humans

• The dose that is lethal to 50% of a population of test animals is called the LD50

• The smaller the LD50 , the more toxic the chemical

Determining Health Effects of Pollutants


Dose-Response Curve• Dose-response curve

– A graph that shows the effects of different doses on a population of test organisms

– Evidence suggests that there is not a safe dose for certain toxicants

The figure on the left shows the response increases as the dose increases and harmful response is above threshold; on right, A has a lower ED50 than B, however B more toxic than A at lower doses

Dose-Response StudiesDose (hypothetical units) Percent Mortality

1 0%2 0%3 4%4 10%5 40%6 60%7 90%8 96%9 100%

10 100%

LD50 = 5.3

LD50

Do The Math• If the LD50 of a pesticide is 20 mg/kg for a

mouse, what amount would be considered safe to ingest for a human?

• (Calculate the “safe” amount by taking the LD50 and dividing it by 1,000)

20 mg/kg ÷ 1000 = 0.02 mg/kg• Calculate the maximum amount that a 80 kg

man could ingest and still be considered “safe”80 kg × 0.02 mg/kg = 1.6 mg

Poisons• Poisons: materials that kill at a

very small dose (50 milligrams or less per kilogram of weight)


• The dose at which 50% of a population will exhibit the response under study (ED50)

• Threshold level– The maximum dose at

which the toxicant has no measurable effect

– Doses lower than threshold level are considered safe

• This scientist is measuring a toxicant in human blood serum

Determining the Health Effects of Pollutants

Threshold


Cancer-Causing Substances• Carcinogens are any substance that causes cancer• Most common method of determining cancer-causing agent is to

expose groups of laboratory animals to various doses and count how many animals develop cancer

– Indirect and uncertain– Humans and laboratory animals may respond differently to chemical

exposure– Laboratory animals generally exposed to massive doses relative to their

body size– Risk assessment assumes we can extrapolate from these experiments,

determining expected cancer rates in humans and the safety of some chemicals—assumptions that may over or underestimate a toxicant's danger

• EPA working with toxicologists to develop direct evidence of risk involved with exposure to low doses of cancer-causing chemicals


Risk Assessment of Chemical Mixtures• Although humans are exposed to combinations of chemical

compounds in air, food and water, most studies are done on single chemicals– Mixtures of chemicals increase level of complexity in risk assessment – Too many chemical mixtures to evaluate– Chemical mixtures interact by one of three ways: additivity, synergy, or

antagonism

• Additivity: the additive effect of each component of the mixture– Additivity is generally used in order to asses the risk for chemical mixtures

• Synergy: the mixture has a greater combined effect than the chemicals individually

• Antagonistic: mixture has a smaller combined effect than the chemicals individually

Interactions• Synergistic interactions: when two (or more)

risk factors have a greater effect together than each by themselves– Ex: being exposed to asbestos and smoking gives

you a 400 times greater chance of developing lung cancer than if you experienced only one of those risks

+ =


Children and Chemical Exposure• Children are more

susceptible than adults– Weigh less than adults– Interact more with their

environment– Undergoing growth and

development – Higher metabolic rate,

requires more oxygen (increased susceptibility to air pollution)

1990 study in Los Angeles found that 80% of children who died for reasons other than respiratory disease had early stage lung disease


EnviroDiscovery Smoking: A Significant Risk

• Single largest cause of preventable death

• Causes serious diseases– Lung cancer, emphysema, heart disease,

premature death

• Passive smoking also increases risk of cancer

• Fewer in developed nations smoke and public bans working

• Smoking is increasing in developing nations

• 2005 international treaty to ban tobacco advertising worldwide


The Precautionary Principle• The idea that we should not

adopt a new technology, practice, or material until it is demonstrated that:– The risks are small– The benefits outweigh the

risks

• Puts the burden of proof onto the developers

• “An ounce of prevention is worth a pound of cure”

These city kids are probably exposed to lead in the soil (from leaded gasoline)


The Precautionary Principle: Common Sense?

• There is also controversy– Scientists feel it endorses the

making of decisions without the input of science

• The EU (European Union) banned beef from U.S. and Canada because of the use of hormones to make cattle grow faster

• The EU uses precautionary principle with respect to GMOs (genetically modified organisms)

• Precautionary principle or economic protectionism?


Case Study: Endocrine Disrupters• Many industrial and agricultural

chemicals are endocrine disrupters • Some disrupters mimic hormones • Can cause reproductive disorders,

infertility, and hormonally-related cancers

• Congress amended Food Quality Protection Act and Safe Drinking Water Act of 1996 – EPA to develop plan to establish testing for

potential endocrine disruptors

• Lake Apopka, Florida, alligators have abnormalities in their reproductive systems

rank the following causes of death from highest to lowest probability earthquake lightning stroke...

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